Pentachloronitrobenzene
(
PCNB)
Summary
August
18,
2004
Uses
°
PCNB
is
an
organochlorine
fungicide
used
to
control
diseases
on
vegetables
(
predominantly
cole
crops
and
green
beans),
field
crops
(
cotton,
potatoes,
and
peanuts),
turf,
ornamentals
and
seeds
(
seed
treatments
of
barley,
beans,
corn,
cotton,
oats,
peas,
peanut,
potato,
safflower,
sorghum,
soybean,
sugar
beet,
and
wheat).
It
is
applied
to
soil,
foliage
(
for
turf
uses),
and
seeds.
°
There
are
tolerances
for
PCNB
[
CFR
180.291
and
180.319]
on
14
commodities:
cottonseed,
collards,
kale,
mustard
greens,
bean,
broccoli,
brussels
sprouts,
cabbage,
cauliflower,
garlic,
pepper,
potato,
tomato,
and
peanuts.

Health
Effects
°
A
database
uncertainty
factor
of
10X
has
been
applied
to
the
dietary
and
residential/
recreation
risk
assessments
in
the
absence
of
comparative
thyroid
data.
°
Generally,
PCNB
has
low
acute
toxicity,
with
most
study
results
in
Toxicity
Categories
III
or
IV,
but
in
one
study
(
Uniroyal)
PCNB
was
identified
as
a
weak
sensitizer.
°
Effects
associated
with
PCNB
in
longer­
term
studies
are
predominantly
thyroid
and
liver
effects.
°
PCNB
is
classified
as
a
Group
C
(
possible
human)
carcinogen.
Evidence
of
carcinogenic
effects
is
weak
and
carcinogenic
potenial
is
not
quantified.

Dietary
Risk
from
Food
°
No
adverse
effects
attributed
to
a
single
exposure
(
dose)
were
identified,
so
no
acute
dietary
risk
assessment
was
necessary.
°
The
chronic
dietary
risk
(
food
alone)
for
PCNB
does
not
exceed
the
Agency's
level
of
concern
(
i.
e.,
less
than
100%
of
the
chronic
PAD
is
utilized)
for
registered
and
nonregistered
crops.

Dietary
Risk
from
Drinking
Water
°
No
adverse
effects
attributed
to
a
single
exposure
(
dose)
were
identified,
so
no
acute
drinking
water
risk
assessment
was
necessary.
°
Estimated
drinking
water
concentrations
(
EDWC)
for
surface
water
bodies
(
chronic
44.2
ug/
L
(
ppb))
were
determined
using
the
Tier
II
screening­
level
simulation
models
PRZM
(
v.
3.12)/
EXAMS
(
2.98.04).
The
Tier
1
screening
model
SCI­
GROW
(
Screening
Concentrations
in
Ground
Water)
was
used
to
calculate
the
groundwater
EDWCs
(
30.6
ug/
L
(
ppb)).

Residential
Handler
Risk
°
Residential
risks
are
of
concern
for
several
scenarios,
including
hand
application
of
granules,
mixing/
loading/
applying
liquids
with
a
low
pressure
handwand
and
hoseend
sprayers,
and
loading/
applying
granules
with
a
belly
grinder.
2
Residential
Post­
application
Risk
°
The
scenarios
likely
to
result
in
residential
post­
application
exposures
are
dermal
contact
for
adults
and
toddlers
to
treated
turf
and
lawns,
and
oral
exposure
to
toddlers
from
ingestion
of
grass,
soil,
or
hand­
to­
mouth
contact.
All
these
scenarios
yielded
MOEs
below
the
target
MOE
of
1000,
and
represent
risks
of
concern.
Toddlers
are
particularly
at
risk.
°
Golfing
and
mowing
lawns
on
the
day
of
application
yielded
MOEs
MOEs
below
the
target
MOE
of
1000,
and
represent
risks
of
concern.

Aggregate
Risk
°
For
PCNB
and
its
metabolites,
aggregate
risk
assessment
was
conducted
only
for
total
dietary
(
food
+
water),
because
the
risks
associated
with
residential
handler
and
post­
application
risk
individually
exceed
levels
of
concern.
°
For
total
dietary
risk
(
food
+
water),
chronic
dietary
risks
exceed
levels
of
concern
for
the
general
population
(
105%
cPAD)
and
most
population
subgroups
(
the
highest
risk
is
for
infants
at
313%
cPAD).
°
PCNB
is
classified
as
a
Group
C
(
possible
human)
carcinogen.
Based
on
weak
evidence
of
carcinogenic
effects
a
reference
dose
approach
was
used,
and
a
dose
response
assessment
for
cancer
was
not
conducted.

Worker
Risk
°
Workers
are
exposed
to
PCNB
during
handling
of
PCNB
through
the
skin
and
via
inhalation,
typically
over
the
short­
and
intermediate­
terms.
°
For
most
occupational
handler
scenarios,
risk
estimates
for
short­
and
intermediate­
term
dermal
exposures
to
PCNB
are
below
EPA's
level
of
concern
with
MOEs
greater
than
or
equal
to
the
target
MOE
of
100,
when
appropriate
PPE
or
engineering
controls
are
employed.
The
following
scenarios
had
MOEs
<
100
at
all
levels
of
PPE
and
engineering
controls,
and
represent
risks
of
concern:
°
mixing/
loading
dry
flowable
for
chemigation
application
(
sod
farms)
°
applying
sprays
for
high
pressure
handwand
application
(
ornamentals)
°
mixing/
loading/
applying
liquid
for
handgun
(
lawn)
sprayer
application
°
mixing/
loading/
applying
granular
for
belly
grinder
application
(
ornamentals)
°
mixing/
loading/
applying
wettable
powders
for
low
pressure
handwand
application
(
ornamentals
­
woody
shrubs
and
vines,
herbaceous
plants,
and
shade
trees)­
shade
trees)
°
All
the
MOE
estimates
for
short­
and
intermediate­
term
inhalation
exposures
are
greater
than
or
equal
to
the
target
MOE
of
100and
are
not
of
concern,
although
some
scenarios
require
the
addition
of
PPE
or
engineering
controls
to
achieve
that
level.
These
scenarios
include:
°
mixing/
loading
dry
flowable
for
chemigation
application
(
sod
farms)
°
mixing/
loading
liquids
for
chemigation
and
aerial
applications
°
mixing/
loading
wettable
powder
for
chemigation
application
(
cole
crops
and
sod
farms)
3
°
mixing/
loading
wettable
powders
for
groundboom
application,
°
applying
sprays
for
high
pressure
handwand
applications
°
mixing/
loading/
applying
wettable
powders
for
low
pressure
handwand
application
(
ornamentals
­
woody
shrubs
and
vines,
herbaceous
plants,
and
shade
trees)
°
Workers
who
treat
seed
with
PCNB
in
smaller
or
on­
farm
facilities,
performing
multiple
activities,
might
require
a
respirator
to
reduce
exposures
so
that
potential
risks
(
MOEs)
would
be
>
100.
°
There
is
a
low
potential
for
occupational
post­
application
exposure
when
a
preplant
or
at
planting
fungicide
such
as
PCNB
is
used.
The
Agency
conducted
a
risk
assessment
for
potential
post­
application
exposures
for
turf
at
golf
courses
and
sod
farms.
Even
on
the
day
of
application,
risks
to
golf
course
workers
or
sod
farm
workers
performing
hand­
harvesting
of
sod
are
equal
to
or
greater
than
the
target
MOE
of
100
and
are
not
of
concern.

Ecological
Risk
°
High
bioconcentration
factors
of
PCNB
(
as
high
as
22,000)
suggest
it
is
very
likely
to
bioconcentrate
and
biomagnify
in
the
aquatic
food
chain.
°
Levels
of
concern
for
chronic
risk
are
exceeded
for
non­
target
birds
and
mammals.
°
Acute
and
chronic
levels
of
concern
are
exceeded
for
freshwater
fish
and
invertebrates.
Acute
levels
of
concern
are
exceeded
for
estuarine/
marine
fish
and
invertebrates.
Chronic
toxicity
data
are
lacking
for
estuarine/
marine
animals.
